The present invention relates to complex esters and amides of phenyl xanthine derivatives, processes for their preparation, pharmaceutical formulations comprising them, and their use in medicine, particularly in the prophylaxis and treatment of septic shock, inflammatory conditions, as well as immune disorders.
Septic shock is induced by means of a complex series of events involving many different pathways and mediators of disease response (see for instance, The Lancet, Vol. 338 (1991), p732-739, and Annals Of Internal Medicine Vol. 115 (1991), p457-469), including, inter alia, products of arachidonic acid metabolism and platelet aggregation.
The adhesion of circulating leukocytes to the vascular endothelium is a crucial event in the pathogenesis of inflammatory responses. Inflammatory and immune mediators can stimulate the adhesion process by increasing the adhesiveness of the leukocyte or the endothelial cell through the activation, upregulation, or induction of various adhesion molecules on the cell surface.
Anti-inflammatory drugs currently available have limited efficacy, often with side effects. Monoclonal antibodies used experimentally for anti-adhesion therapies have theoretical disadvantages for treatment of chronic diseases. Therefore, the discovery and development of small molecules which specifically block or inhibit the adhesive interactions of leukocytes and the endothelium is an attractive area of therapeutic intervention.
PCT Application No. GB 9501808 describes compounds of formula: 
Wherein m and n are independently integers from 0 to 10;
X and Y are independently oxygen or sulphur;
(xe2x80x94Qxe2x80x94) is (xe2x80x94CH2xe2x80x94)p or (xe2x80x94CHxe2x95x90CHxe2x80x94)p where p is an integer of from 1 to 4; and
A and B are independently methyl, branched C3-6 alkyl, C3-8 cycloalkyl or C3-8 cycloalkenyl;
and salts, solvates and pharmaceutically acceptable esters and amides thereof, and their use in treatment of septic shock, allergic, and inflammatory conditions. The compounds had been found to inhibit one or more of the enzymes 5-lipoxygenase, cyclooxygenase, and lyso-PAF: acetyl-CoA acetyltransferase.
We have now surprisingly discovered a series of complex esters and amides of selected phenyl xanthine derivatives which inhibit the expression of adhesion molecules on human umbilical vein endothelial cell (HUVEC) monolayers at very low concentrations and which are therefore indicated for treatment of inflammatory conditions and immune disorders.
Accordingly the present invention provides a compound of formula (I): 
or a solvate thereof wherein:
X is xe2x80x94Oxe2x80x94 or xe2x80x94NHxe2x80x94;
Q is (xe2x80x94CH2xe2x80x94)p, (xe2x80x94CHxe2x95x90CHxe2x80x94)p, (xe2x80x94Cxe2x89xa1Cxe2x80x94)p where p is an integer of from 0 to 4;
R1 is hydrogen or methyl;
R2 and R3 independently represent O or S.
n is an integer of 1 to 50; and
R is hydrogen or methyl.
According to a further aspect, the present invention provides a compound of formula (I) as defined above wherein X is xe2x80x94Oxe2x80x94 or xe2x80x94NHxe2x80x94 and R1 is H; of these, compounds wherein n is an integer of 8 to 20 are preferred, and those wherein n is an integer of 8 to 15 are more preferred.
Conveniently R3 represents O and R2 represents O or S but more preferably R3 and R2 both represent O.
According to a further aspect of the invention, P preferably represents 0 or 1.
According to a further aspect, the present invention provides a compound of formula (I) as defined above wherein Q is (xe2x80x94CHxe2x95x90CHxe2x80x94)p.
Preferably the 
substituent is attached to the phenyl ring in the para position.
The invention also includes mixtures of compounds of formula (I) in any ratio, for example wherein n varies within the same sample.
A particular subgroup of compounds is of formula I a 
or a solvate thereof wherein:
X is xe2x80x94Oxe2x80x94 or xe2x80x94NHxe2x80x94;
Q is (xe2x80x94CH2xe2x80x94)p or (xe2x80x94CHxe2x95x90CHxe2x80x94)p where
P is an interger from 1 to 4;
R1 is hydrogen or methyl
n is an integer of 1 to 50; and
R is hydrogen or methyl.
Particularly preferred compounds of the invention include
(E)-4-(1,3-Bis(cyclohexylmethyl)-1,2,3,6-tetrahydro-2,6-dioxo-9H-purin-8-yl)cinnamic Acid Decaethylene Glycol Methyl Ether Ester;
(E)-4-(1,3-Bis(cyclohexylmethyl)-1,2,3,6-tetrahydro-2,6-dioxo-9H-purin-8-yl)cinnamic Acid Nonaethylene Glycol Methyl Ether Ester;
(E)-3-[1,3-Bis(cyclohexylmethyl)-1,2,3,6-tetrahydro-2,6-dioxo-9H-purin-8-yl]cinnamic Acid Nonaethylene Glycol Methyl Ether Ester;
(E)-4-[1,3-Bis(cyclohexylmethyl)-1,2,3,6-tetrahydro-2,6-dioxo-9H-purin-8-yl)cinnamic acid Nonaethylene Glycol Methyl Ether Amide and
(E)-4-[1,3-Bis(cyclohexylmethyl)-1,2,3,6-tetrahydro-2,6-dioxo-9H-purin-8-yl]benzoic acid Nonaethylene Glycol Methyl Ether Ester or a solvate thereof.
The compounds of the present invention are capable of existing as geometric and optical isomers. All such isomers, individually and as mixtures, are included within the scope of the present invention. Where Q contains a double bond, compounds in the form of the E-geometric isomers are preferred.
As mentioned hereinbefore, compounds of formula (I) and solvates thereof, have use in the prophylaxis and treatment of inflammatory conditions and immune disorders, as demonstrated hereinafter in the biological assays in which representative compounds of the present invention have been shown to be active.
Examples of inflammatory conditions or immune disorders are those of the lungs, joints, eyes, bowel, skin, and heart; particularly those associated with the infiltration of leucocytes into inflamed tissue. Conditions of the lung include asthma, adult respiratory distress syndrome, bronchitis and cystic fibrosis (which may additionally or alternatively involve the bowel or other tissue(s)). Conditions of the joint include rheumatoid arthritis, rheumatoid spondylitis, osteoarthritis, gouty arthritis and other arthritic conditions. Inflammatory eye conditions include uveitis (including iritis) and conjunctivitis. Inflammatory bowel conditions include Crohn""s disease, ulcerative colitis and distal proctitis. Skin diseases include those associated with cell proliferation, such as psoriasis, eczema and dermatitis (whether or not of allergic origin). Conditions of the heart include coronary infarct damage. Other inflammatory conditions and immune disorders include tissue necrosis in chronic inflammation, endotoxin shock, smooth muscle proliferation disorders (for example, restenosis following angioplasty), and tissue rejection following transplant surgery.
Accordingly, the present invention provides a method for the prophylaxis or treatment of an inflammatory condition or immune disorder in a mammal, such as a human, which comprises administration of a therapeutically effective amount of a compound of formula (I), or a pharmaceutically acceptable solvate thereof. The present invention further provides a method for the prophylaxis or treatment of septic shock in a mammal, such as a human, which comprises administration of a therapeutically effective amount of a compound of formula (I), or a pharmaceutically acceptable solvate thereof.
In the alternative, there is also provided a compound of formula (I), or a pharmaceutically acceptable solvate thereof for use in medical therapy; particularly, for use in the prophylaxis or treatment of an inflammatory condition or immune disorder in a mammal, such as a human. The present invention further provides a compound of formula (I), or a pharmaceutically acceptable solvate thereof for use in the prophylaxis or treatment of septic shock.
The amount of a compound of formula (I) or pharmaceutically acceptable solvate thereof, which is required to achieve the desired biological effect will depend on a number of factors such as the use for which it is intended, the means of administration, and the recipient. A typical daily dose for the treatment of septic shock, for instance, may be expected to lie in the range of 0.005 mg/kg-100mg/kg, preferably 0.5-100 mg/kg, and most preferably 0.5-20 mg/kg. This dose may be administered as a single unit dose or as several separate unit doses or as a continuous infusion. An intravenous dose may be expected to lie in the range of 0.0025 mg/kg to 200 mg/kg and would typically be administered as an infusion. Similar dosages would be applicable for the treatment of other disease states. For administration to the lungs of a subject by aerosol an amount of the compound should be used sufficient to achieve concentrations on the airway surface liquid of the subject of about 2 to 1000 xcexcmol.
Thus, in a further aspect of the present invention, there are provided pharmaceutical compositions comprising, as active ingredient, a compound of formula (I) or a pharmaceutically acceptable salt or solvate thereof, together with at least one pharmaceutical carrier or recipient. These pharmaceutical compositions may be used in the prophylaxis and treatment of conditions such as septic shock, inflammatory conditions, and immune disorders. The carrier must be pharmaceutically acceptable to the recipient and must be compatible with, i.e. not have a deleterious effect upon, the other ingredients in the composition. The carrier may be a solid or liquid and is preferably formulated as a unit dose formulation, for example, a tablet which may contain from 0.05 to 95% by weight of the active ingredients. If desired other physiologically active ingredients may also be incorporated in the pharmaceutical compositions of the invention.
Possible formulations include those suitable for oral, sublingual, buccal, parenteral (for example subcutaneous, intramuscular, or intravenous), rectal, topical including transdernal, intranasal and inhalation administration. Most suitable means of administration for a particular patient will depend on the nature and severity of the condition being treated and on the nature of the active compound, but where possible, iv administration is preferred for the treatment of septic shock, for instance. For the treatment of a condition such as asthma, however, oral or inhalation, would be the preferred route of administration.
Formulations suitable for oral administration may be provided as discrete units, such as tablets, capsules, cachets, lozenges, each containing a predetermined amount of the active compound; as powders or granules; as solutions or suspensions in aqueous or nonaqueous liquids; or as oil-in-water or water-in-oil emulsions.
Formulations suitable for sublingual or buccal administration include lozenges comprising the active compound and, typically a flavoured base, such as sugar and acacia or tragacanth and pastilles comprising the active compound in an innert base, such as gelatine and glycerine or sucrose acacia.
Formulations suitable for parenteral administration typically comprise sterile aqueous solutions containing a predetermined concentration of the active compound; the solution is preferably isotonic with the blood of the intended recipient. Although such solutions are preferably administered intravenously, they may also be administered by subcutaneous or intramuscular injection.
Formulations suitable for rectal administration are preferably provided as unit-dose suppositories comprising the active ingredient in one or more solid carriers forming the suppository base, for example, cocoa butter.
Formulations suitable for topical or intranasal application include ointments, creams, lotions, pastes, gels, sprays, aerosols and oils. Suitable carriers for such formulations include petroleum jelly, lanolin, polyethyleneglycols, alcohols, and combinations thereof. The active ingredient is typically present in such formulations at a concentration of from 0.1 to 15% w/w.
Formulations of the invention may be prepared by any suitable method, typically by uniformly and intimately admixing the active compound with liquids or finely divided solid carriers or both, in the required proportions and then, if necessary, shaping the resulting mixture into the desired shape.
For example a tablet may be prepared by compressing an intimate mixture comprising a powder or granules of the active ingredient and one or more optional ingredients, such as a binder, lubricant, inert diluent, or surface active dispersing agent, or by moulding an intimate mixture of powdered active ingredient and inert liquid diluent.
Aqueous solutions are typically prepared by dissolving the active ingredient in saline to which cyclodextrin has been added.
Suitable formulations for administration by inhalation include fine particle dusts or mists which may be generated by means of various types of metered dose pressurised aerosols, nebulisers, or insufflators.
For pulmonary administration via the mouth, the particle size of the powder or droplets is typically in the range 0.5-10 xcexcm, preferably 1-5 xcexcm, to ensure delivery into the bronchial tree. For nasal administration, a particle size in the range 10-500 xcexcm is preferred to ensure retention in the nasal cavity.
Metered dose inhalers are pressurised aerosol dispensers, typically containing a suspension or solution formulation of the active ingredient in a liquefied propellant. During use, these devices discharge the formulation through a valve adapted to deliver a metered volume, typically from 10 to 150 xcexcl, to produce a fine particle spray containing the active ingredient. Suitable propellants include certain chlorofluorocarbon compounds, for example, dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane and mixtures thereof The formulation may additionally contain one or more co-solvents, for example, ethanol surfactants, such as oleic acid or sorbitan trioleate, anti-oxidants and suitable flavouring agents.
Nebulisers are commercially available devices that transform solutions or suspensions of the active ingredient into a therapeutic aerosol mist either by means of acceleration of a compressed gas typically air or oxygen, through a narrow venturi orifice, or by means of ultrasonic agitation. Suitable formulations for use in nebulisers consist of the active ingredient in a liquid carrier and comprising up to 40% w/w of the formulation, preferably less than 20% w/w. The carrier is typically water or a dilute aqueous alcoholic solution, preferably made isotonic with body fluids by the addition of, for example, sodium chloride. Optional additives include preservatives if the formulation is not prepared sterile, for example, methyl hydroxy-benzoate, anti-oxidants, flavouring agents, volatile oils, buffering agents and surfactants.
Suitable formulations for administration by insufflation include finely comminuted powders which may be delivered by means of an insufflator or taken into the nasal cavity in the manner of a snuff. In the insufflator, the powder is contained in capsules or cartridges, typically made of gelatin or plastic, which are either pierced or opened in situ and the powder delivered by air drawn through the device upon inhalation or by means of a manually-operated pump. The powder employed in the insufflator consists either solely of the active ingredient or of a powder blend comprising the active ingredient, a suitable powder diluent, such as lactose, and an optional surfactant. The active ingredient typically comprises from 0.1 to 100 w/w of the formulation.
Therefore, according to a further aspect of the present invention, there is provided the use of a compound of formula (I) or a pharmaceutically acceptable solvate thereof in the preparation of a medicament for the prophylaxis or treatment of an inflammatory condition or immune disorder.
Compounds according to the invention can be made according to any suitable method of organic chemistry. Therefore, according to a further aspect of the invention, there is provided a process for preparing the compounds of formula (I), or solvates thereof which comprises reacting the compound of formula (II) 
or an activated derivative thereof with a compound of formula (III) 
wherein Q, X, R1, R, R2 and R3 and n are as hereinbefore defined.
and optionally converting the compound of formula (I) so formed to a different compound of formula (I) or to a corresponding solvate.
When X is oxygen, the esterification may be effected by standard methods, for example using an acid catalyst and, optionally, an inert solvent such as toluene, benzene, or a xylene. Suitable acid catalysts include mineral acids; for example, sulphuric acid, hydrochloric acid, and phosporic acid; and organic acids; for example, methanesulphonic acid, or toluenesulphonic acid. The esterification is typically carried out at elevated temperature, for example, 50-150xc2x0 C., preferably with removal of the water formed by distillation.
Where X is oxygen or xe2x80x94NHxe2x80x94, the reaction may be effected by first preparing an activated derivative of the compound of formula (II). Suitable activated derivatives include activated esters or acid halides and may either be isolated before reaction with the compound of formula (III) or prepared in situ. Particularly useful activated esters of the compound of formula (II) are acylimidazoles which are readily prepared by reaction of the compound of formula (II) with N, N1-carbonyldiimidazole.
Conversion of an activated derivative of the compound of formula (II) to a compound of formula (I) may be effected in an inert solvent, optimally in the presence of a non-nucleophilic base, such as potassium t-butoxide, sodium hydride, or a non-nucleophilic organic base, such as 1,8-diazabicylo [5.4.0] undec-7-ene.
The compound of formula (II) may be prepared as described in PCT application No. GB 9501808.
Compounds of formula (III) are commercially available or may be prepared by literature methods. For example, R. A. Bartsch et al, J. Org. Chem. 1989, 54: 857-860 and J. M. Harris, Macromol. J.Sci. Rev. Polymer Phys. Chem. 1985, C25 (3): 325-373, and S. Zalopsky, Bioconjugate Chem. 1995, 6: 150-165.
Alternatively, compounds of formula (I) may be prepared by condensation of a compound of formula (IV) 
or an acetal derivative thereof,
wherein Q, X, R1, n and R are as hereinbefore defined, with 1,3-bis(cyclohexylmethyl)-5,6-diaminouracil (which may be prepared as described in the Examples). The condensation is suitably carried out in a polar solvent at nonextreme temperature as described in PCT Publication No. WO96/04280, published Feb. 15, 1996.
Compounds of formula (IV) may be prepared by coupling a compound of formula (III) with the appropriate carboxylic acid. Methods for effecting this coupling and for preparing the carboxylic acid are described in PCT Publication No. WO96/04280, published Feb. 15, 1996.
Conversion of a compound of formula (I) to a solvate thereof may be effected by standard methods known to a person skilled in the art.